Stockholders' Equity (Summary Of Shares Repurchased) (Details)	12 Months Ended
	Dec. 31, 2016 item shares	Dec. 31, 2015 USD ($) shares	Dec. 31, 2014 USD ($) shares
Stockholders; Equity, Common Stock Issued and Outstanding [Abstract]
Purchase of Treasury Stock | $		$ 250,000,000	$ 375,000,000
Shares repurchased | shares	0	5,967,313	6,373,718
Number of open share buyback programs | item	0